Block signal system



Feb. 11, 1936, c, sun-s 2,03Q,662

' BLOCK SIGNAL SYS'ITEM Filed Dec. 5, 1929 2 Sheets-Sheet l Invent or: Ghauncgg 6. Suits C. G. SUITS BLQCK SIGNAL SYSTEM Filed Dec. 5, 1929 W -1 2 Sheets-Sheet 2 InvntoP: I Chaunce g GJSuLts, QB

His Attorngg.

Patented Feb. 11, 1936 umrse $TATES BLOCK SIGNAL SYSTEM Chauncey G. Suits, Madison, Wis., assignor to General Electric Company, a corporation of New York Application December 5, 1929, Serial No. 411,929

28 'Claims.

My invention relates to railway' block signal systems, and it has for one of its objects to provide a signal system which operates entirely electrically.

A further object of the invention is toprovide certain improvements in systems of the type indicated whereby the signals of such a system may be more satisfactorily and reliably controlledthan has been possible heretofore.

A further object of the invention is to provide means whereby the signals of an occupied block and also those of the adjacent blocks may be controlled in accordance with the condition of the different blocks through means entirely electrical.

1.; Thus, for example, in the usual form of signal system, means are provided whereby the signal or signals at the entrance of a block which is occupied by a vehicle are caused to indicate danger" and, the signal or signals at the entrance to the 20 block at the rear of the vehicle are caused to indicate caution the latter indication being frequently dependent upon the presence of a following vehicle in the second block to the rear. It is also well known signal practice to have all of the 25 signals normally deenergized and to provide means whereby when a vehicle enters any block the signals of the block in advance indicate safe" or clear dependently upon the condition of the advance block.

3:? Thus one of the objects of my invention is to provide means entirely electrical whereby the signals may be controlled in accordance with well-known practices and in which both the can tion and safe signals may be operated in re- :13 sponse to the movements of a vehicle and dependently upon the position of other vehicles upon the track.

In carrying my invention into efiect I provide an electron discharge device in each block which 4') is controlled in accordance with track conditions, that is, in dependence upon the occupancy of the respective block by a vehicle. The anode current of each of these discharge devices is then employed to control a number of reactors located in i; the blocks at which signals are to be controlled. These reactors are of the iron core type and have a winding of which the impedance varies over a wide range dependently upon the degree of saturation of the core. These windings are em- .31 ployed to control the energization of the different signals in response to operation of the discharge devices and hence in accordance with track conditions.

By means of the type indicated the signals may or. be controlled as is desired in accordance with well known signal practice and by means employing a minimum of discharge devices and, as will later appear, a minimum of line conductors extending between adjacent blocks.

Thus a further object of the invention is to 5 provide means entirely electrical whereby the desired signal operation may be carried out and which employs a minimum of discharge devices.

By the expression entirely electrical as used in this application I have reference to a system 10 in which all of the component parts are maintained in fixed mechanical relation and the operative effect of which is due entirely to electrical conditions within'the structure. Such a system may be considered, for example, in contrast to a system the operative eifect of which is due to a mechanical movement, such as that of the armature of an electro-mechanical relay.

A still further object of the invention is to provide means including the reactors above indicated for controlling the different signals in accordance with track conditions.

While in the following specificationl will describe a particular means for controlling the grid circuits of different discharge devices of the system, it will be'understood that I am not to be limited thereto, and that any suitable means may be employed to control the different discharge devices in dependence upon the presence of a vehicle in the respective blocks.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof, may best be understood by reference to the following description'taken in connection with the accompanying drawings in which Figs. 1, 2, 4 and 5 represent different embodiments of my invention, and Figs. 40 3 and 6 represent modifications thereof.

Referring to Fig. l of the drawings I have represented at l the tracks of a railway system. This track is divided into blocks A, B, C etc. in accordance with common practice, the rails of the diiferent blocks being electrically insulated from each other as indicated at the points 2, 3, 4, etc. At 5, 6 and 1 I have indicated the signaling equipments which are associated with each of the blocks A, B, and C respectively. These equipments are all identical in circuit arrangement, and it will be understood that a similar equipment is associated with each of the different blocks of the railway system.

While any suitable system of signals may be employed in the equipments 5, 6, l I have shown a plurality of lamps which upon illumination indicate the different track conditions as, for example, when the lampR is energized, the occupied condition of the block A or danger is indicated. When the lamp Y is energized the occupied condition of the adjacent block B in the direction of traffic or caution is indicated, and when the lamp G is energized the clear or safe condition of both of the above mentioned blocks is indicated.

,1 have indicated at 8 a power supply. circuit which is normally energized from a source 9 and which may extend throughout the railway system. Energy from the power supply circuit 8 is supplied through transformers Ill, l0, ill" to the exit end of each of the-blocks A, B, C respectively, a suitable resistance being included in the circuit for adjusting the magnitude of the electro-motive force supplied to'each of the different blocks as desired. At the entrance end of each of the blocks this energy from the track circuit is supplied through transformers II, II, I!" to the grid circuit of electron discharge devices I2, l2, l2. It will thus be apparent that the grid circuit of each of the discharge devices associated with the different blocks is normally supplied with alternating current from the track rails, but that upon the entrance of a vehicle, such as a locomotive, in any of the blocks, the two rails become short circuited through the. wheels and axles of the vehicleand the alternating electromotive force is removed from the grid circuit of the corresponding electron discharge device. These discharge devices are connected in a manner presently to be described to control the signal devices R, Y, G; R, Y, G; R", Y", G in each of the respective blocks. Thus, for example, when alternating current is removed from the grid of any of the discharge devices the danger signal in the respective block, and certain of the other signals will become actuated as will presently be indicated.

It will be noticed that the grid circuit of each of the discharge devices is thus one which is inherently protected against faults, such as may occur due to a broken rail, short circuit power supply or any other fault which may in- "terrupt the supply of alternating current to the grid of the respective discharge device. Any such interruption has the same effect upon-the system as that produced by the presence of a.

vehicle in the respective blocks, that is, to cause a danger indication to be given.

The anode circuit of each of the discharge devices is energized from the power supply circuit 8 and includes a plurality of saturated core reactors which I have indicated in the drawings at l3|9 in the equipment 5, l3l9 in the equipment 6, and I3"-I 9 in the equipment 1. These reactors may be of any suitable construction, but

7 each comprises a direct current winding and an alternating current winding arranged upon an iron, or ferro-magnetic core such that when the direct current winding is energized the iron core becomes saturated and the alternating current winding becomes of low impedance, whereas when the direct current winding is unenergized the alternating current winding is of high'impedance; In thedrawings I have indicated a bar adjacent the direct current winding of each reactor for the purpose of rendering this winding distinctive.

parallel circuits comparatively low in of the The signals R, Y, G in the difeach of these circuits including limiting reactors for purposes later to be indicated. Energization of each of the signals thus connected is controlled by the alternating current windings of the different reactors in accordance with track conditions.

The discharge devices l2, l2, l2" etc. may be of any suitable construction, but preferably these devices are of the vapor electric type having an anode, a cathode and a grid enclosed in an envelope provided with a conducting gas such as mercury vapor. These discharge devices have the characteristic that their impedance is changed from a very high value to one which is response to a very small change in grid voltage; that is, as the alternating current grid voltage is gradually increased in a positive direction the anode circuit suddenly changes from a very high impedance to a very low impedance, in which condition the discharge device has the capacity to carry a very large When the alternating current grid pedance from a high value to a low'value occurs is substantially that at which it changes from a low value to a high value. This character of the discharge device, as indicated, renders it particularly well adapted for the purpose to be herein described since, particularly in wet weather conditions, the voltage variations in response to which the signals are operated are very narrow;

A further understanding of the invention as illustrated in Fig. 1 may now best be had by ref-- erence to its operation. Normally direct current flows in the anode circuit of each of the dis charge devices, and the difierent reactors are saturated and their secondary windings are of very low impedance. Considering, for example, the equipment 6 it will be noticed that the alternating current winding of reactor 19 is connected directly in shunt with the lamp R, such that this lamp is normally short circuited and deenergized. In the same way the lamp Y is short circuited by the alternating current windings of the reactor IS in equipment 5, and that of reactor l3" in equipment 1. Similarly the lamp G is short circuited by the alternating current winding of reactor l5 in the equipment 5. Thus the signal lamps in each of the different blocks are normally deenergized and unlighted.

Let us assume now that a vehicle enters block A traveling in the direction of the arrow, which I have shown therein for the purpose of indicating the direction of traific, Alternating current is removed from the grid of discharge device I2, thereby causing the direct current windings of each of the reactors 13 to H! to be deenergized. The alternating current winding of reactor then becomes of high impedance thereby causing the lamp R to be lighted, this lamp being connected directly across the power circuit in series with limiting reactor 20. The lamp R thus indicates the occupied condition of block A. Deenergization of the direct current winding of reactor IG causes its secondary winding to become of high impedance, but this has no effect'upon the lamp Y, of equipment 6, whichis connected in shunt therewith, for the reason that this lamp is still short circuited by the alternating current winding of reactor I3". The alternating current winding of reactor l5 now becomes of high imment 6 to become lighted, this lamp being energized in a circuit which extends from one side of the circuit 8 through limiting reactor 22, lamp G, alternating current winding of reactor M which is now of low impedance and alternating current winding of reactor l8 which is also of'low impedance to the opposite side of the circuit 8. The lamp R indicates the occupied condition of the block A, and the lamp G indicates the unoccupied or clear condition of the blocks B and C.

Now let us assume that the vehicle passes from block A to block B. Alternating current is again supplied to the discharge device I2 and is removed from the grid of discharge device I2. Lamp R is again short circuited by the alternating current winding of reactor IS. The shortcircuit about lamp R is removed by reactor l9 and this lamp becomes energized. The lamp G will be lighted in the circuit extending through limiting reactor 22" alternating current winding of reactor [4" and thence to the next block through elements corresponding to those of the circuit previously traced in connection with lamp G. It will be noticed that the lamp Y in block A will not be lighted since it is short circuited by the reactor corresponding to reactor [6 of the equipment in the block to the right of block A.

If we assume that there is a vehicle in blocks A and C and none in block B, the lamp Y will be lighted through a circuit extending from one side of the power source through limiting reactor 2|, lamp Y, and alternating current winding of reactor I'! to the other side of the power source. The lamp G will not be lighted since its circuit includes the high impedance of the alternating current winding of reactor I8". The lamps R" and R will both be lighted.

It will thus be seen that in this system the caution signal Y is not lighted in the block to the rear of a vehicle proceeding along the track unless the second block in the rear is occupied by a vehicle. The danger signal is always given when any block becomes occupied. The clear signal is given in response to the approach of the vehicle in the adjacent block.

Referring to Fig. 2 of the drawings I have shown a considerably simplified system by means of which the above results may be accomplished, and which employs a considerably reduced number of line conductors extending between each of the adjacent blocks. The track or grid circuits of each of the discharge devices in this figure and in the remaining figures are similar to those indicated in Fig. l.

' The anode circuits of the discharge devices may be understood by tracing the anode circuit of the device l2 associated with block B, since this circuit is completely illustrated in the drawings.

It will be seen that this circuit is divided into three branches, one of which extends from the anode of the discharge device. l2 through direct current windings of reactors 23 and 24 in the equipment 5 to the upper conductor of the power supply circuit 8, and thence back to the cathode of device I2. The second branch extends through the direct current windings of reactors 26 of the equipment 6 tothe upper conductor of the circuit 8. A third branch extends through the direct current winding of reactor 21" in the equipment 1. The anode circuits of each of the other discharge devices are identical with the circuit traced.

Thus, if we assume that the block B is occupied by a vehicle, the above branch circuits are deenergized- The deenergization of reactor 24 will cause the lamp Y to be lighted since the direct current winding of reactor 26 is energized and, hence, its alternating current winding is of low impedance. The alternating current winding of reactor 23 becomes of high impedance but has no effect upon the signal G since this signal is short circuited by the alternating current winding of reactor 21. Deenergization of reactor 25 causes the lamp R to be lighted indicating the occupied condition of the block B. Deenergization of reactor 26 has no effect upon signals Y, G, since these signals are both short circuited by reactors 24 and 21. Deenergization of reactor 21" causes the light G to be lighted, since reactors 23 and 26" are both supplied with direct current, and their alternating current windings are of low impedance.

Thus with a vehicle in block B, the lamp G in block C is lighted, lamp R in block B is lighted, and the lamp Y in block A is lighted. If adjacent blocks are occupied the danger signal R in each block will of course become energized.

Thus in this system the caution signal in the block immediately at the rear of a vehicle moving along the track always becomes energized independently of a following vehicle in the second block to the rear. To make the lighting of this signal dependent upon the presence of a following vehicle a slight modification, indicated in Fig. 3 may be made. In accordance with this modification of the system not only the direct current from the advance block is caused to pass through reactor 24' but also that which flows from the rear block also passes through this reactor. Thus the reactor 24, and similarlyreactors 24 and 24", is connected in series both with reactors 23 and 21', which are included in the conductors extending to the opposite adjacent blocks. Thus the alternating current winding of reactor 24' will comprise a substantial short circuit to the lamp Y, except when direct current is removed therefrom by deenergization of both of discharge devices I2 and I2, as

when both blocks A and C are occupied and blockB is unoccupied.

In Fig. 4 I have shown a further embodiment of my invention in which the signals are controlled by means employing a single line conductor extending between the adjacent blocks. The control of signals in advance of a vehicle in any block is effected by increasing the magnitude of direct current flowing in the line circuit extending to the advance block. The control of signals of the block at the rear of a vehicle is effected by diminishing the current in the line conductor extending to that block.

The anode circuits of each of the discharge devices may be understood by tracing the circuit of the device [2. This circuit extends from the upper conductor of the circuit 8 to the cathode and anode of discharge device l2, secondary winding of transformer 29, direct current winding of reactors 25', 26 and 28', in the equipment 6, secondary winding of transformer T in block 5 and direct current windings of reactors 23 and 24 of the equipment 5 to the upper conductor of circuit 8. This circuit is energized by transformer 29' and transformer T connected in series aiding relation for a purpose later to be indicated. It w ll be seen that the reactors 35, 30, 30", which are connected in the anode circuits of the respective discharge devices I 2, l2, l2" each constitute a normal short circuit to the secondary Winding of the respective transformer the direct current flowing in the anode circuit.

T, T, T" such that the principal electromotive force on. the anodes of the different discharge devices is that supplied thereto by the respective transformers 29, 29", 29". However, when the reactor 30 becomes deenergized the anodepo tential on the discharge device I Z" is increased by adding to that of-the secondary winding of transformer 29" the potential on the secondary winding of the transformer T, thereby increasing of device [2.

Thus, for example, let us assume that a vehicle occupies the block B, and that the blocks in the direct current windings thereof. When the increased current in reactor 28 occurs, due to block B being occupied, however, reactor 28" becomes fully saturated and since reactors 23 and 26" are simultaneously saturated the lamp G will be caused to light. The de'energization of the anode circuit of discharge device I2 causes the short circuit to be removed from lamp R and'this lamp is accordingly lighted. Similarly deenergization of this circuit causes a short circuit about lamp Y in block A to be removed, and since reactor 26 is now of low impedance the lamp Y lights. Thus in this system, as shown, the caution signal is energized in the block to the right of an occupied block independently of the presence of a following vehicle in the next ad- 'jacent block. It will, of course, be apparent that if the adjacent blocks are occupied the danger signals in both blocks will be lighted.

' In Fig. 5 I have shown further means whereby the desired signals may be effected by the use of a single line conductor extending between the blocks. In this figure the forward actuation is produced by supplying alternating current over the line extending to the forward block and the rearward actuation is produced by the control of direct'current flowing to the rear block. In this system it will be noticed that the danger signals R, R, R" are connected as before directly across the power supply conductors, whereas the caution and clear signals are energized in a circuit which extends through the conductor leading to the rear block and the transformer t, t, t in the rear block. Thus, for example, the circuit of the lamp G extends from the upper conductor of the power circuit 8 through the alternating current windings of reactors 26', 23, signal G, condensers 3|, 32, limiting reactor 33, secondary winding of transformer t back to the upper conductor of the power supply. The secondary windings of the transformers t, t, t" however, are subject to control of the discharge device in the corresponding block through reactors 34, 34', 34" respectively. The direct ourcause the clear signal in the advance block to ciently reduced to prevent suflicient energization of the clear'signal controlled thereby to cause it to light, but at the same time is sufilcient to maintain-the impedance of the secondary circuit of the respective transformers t, t, t" suificiently high'to prevent excessive current when the reactors 34, 34, 34" are saturated.

Let us assume that the block B is occupied. The anode circuit of the device [2' is then deenergized causing the lamp R tobe lighted. The low impedance shunt to transformer t is removed'and alternating current is then supplied to the lamp G causing it to light. Reactors 23 and 24 are desaturated preventing energization of the lamp G in the rear block and causing the lamp Y in the rear block to be lighted dependently upon the presence of a vehicle in the block to the right of block A. Thus in this: figure the caution signal in the block immediately at the rear of a vehicle becomes energized dependently upon the presence of a following vehicle in the second block at the rear.

. The purpose of reactor 39 and condensers 3| and 3 2- in the equipment 5 and the corresponding elements in equipments 6 and l is to render the alternating and direct current circuitswhich are superposed upon the single line conductors independent of each other. V

In signal systems as practically imployed it may occur that the phase relation between the power supply in the different blocks may vary. Thus, for example, the signal circuits in a certain block may be supplied from a separate distribution system from that of an adjacent block and a considerable difference in phase may exist between the two systems. Accordingly, it may occur that alternating current is applied to the grid of a discharge device of the system from the power supply circuit of one block and to the anode circuit of said discharge'device from the operation of the discharge device. When this condition is encountered, the desired operation may be had by rectifying the potential which is applied to the grid as shown in Fig. 6. In this figure potential which is supplied to the grid of the discharge device from the: track through transformer I l is rectified by means of a rectifier of any suitable type such, for example, as those comprising a copper plate having cuprous oxide formed thereon and mounted between suitable electrodes, as disclosed in Patents No. 1,640,335 to Lars O. Grondahl, issued August 23, 1927. This rectifier, it will be seen, is connected directly in series with the transformer I l and smoothing condenser 36. This condenser is connected directly between the cathode and grid of the discharge device l2. The rectifier 35 is of course unilaterally conducting causing the condenser to charge during the positive half cycles whereupon the charge is maintained by the condenser.

through the alternate half cycle. 7

It may also occur in the operation of systems of the type disclosed that the discharge in the vapor electric devices may fail to cease upon the removal of alternating electromotive force from the grid, this may, for example, be due to the presence of foreign gases within the envelope,

high gas pressure, or electron emission, under certain conditions, from the grid. To protect against an occurrence of this nature, I have provided means which I have shown in connection with Fig. 4 for purposes of illustration. It will be apparent however that these protective means, now to be described, are equally applicable to each of the different systems described.

Associated with each of the electron discharge devices in Fig. 4 is a protective discharge device indicated at 12 I2 and I2 Grid potential for the operation of these protective devices is supplied from the track through an additional secondary winding on the associated grid transformer H, H, II". The winding of the transformers l I, l I, H which is connected to the grid of the protective discharge device is also connected in series with the secondary winding of an additional transformer 31, 31', 31". The primaries of these latter transformers are connected directly across the power circuit. Thus, included in the grid circuit of the discharge devices are two sources of potential comprising the two secondary windings. These windings are so connected that their potentials are in opposed phase relation, such that normally the potential upon the grid of the discharge device is such that no current flows in the anode circuit of the discharge device. Thus, the protective discharge devices IZ lZ I2 are normally inactive, while the discharge devices l2, l2, l2" are normally active. The anode circuit of each of these protective discharge devices includes a resistance 38, 38, 38 which resistance is also in circuit with the primary winding of transformers 29, 29, 29", which normally supply excitation to the anode circuits of the respective discharge devices l2, l2, l2.

If we assume, for example, that the block B becomes occupied by a vehicle, alternating electromotive force is removed from the grid of device I2 and that supplied to the grid of device l2 is increased in proper phase to reduce the impedance of the tube, since there is now no potential across the secondary winding of H to oppose that of transformer 31'. A large current is then caused to flow in the anode circuit of device l2 and thence through resistance 38'. The potential in the resistance 38 occurs during the same half cycle in which the anode of discharge device I2 is positive and, accordingly, so reduces the electromotive force supplied to the,

primary winding of transformer 29' that the anode circuit of discharge device I2 is insufficiently energized to cause the device to operate. Thus the device l2 will become inactive due to operation of the device 12 While I have shown particular embodiments of my invention, it will of course be understood that I do not wish to be limited thereto, since many modifications may be made, both in the circuit arrangement and in the instrumentalities employed, and I contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In a railway block signal system, a single electron discharge device in each block, means for controlling each of said discharge devices in accordance with track conditions in the respective block, means in each block for producing a plurality of indications, and meanscontrolledentirely by said single discharge devices for causing said indicating means to produce indications in accordance with track conditions in the different blocks. 7

2. In a railway block signal system, a single electron discharge device in each block, means for controlling each of said discharge devices in accordance with track conditions in the respective block, means in each block for producing a plurality of indications, and means entirely electrical responsive solely to the anode current in said discharge devices for causing said indicating means to produce indications in accordance with track conditions in the different blocks.

3. In a railway block signal system, a single electron discharge device in each block, means for controlling each of said discharge devices in accordance with track conditions in the respective block, indicating means in each block, and means controlled solely by said discharge devices for causing said indicating means in each block to indicate track conditions in the respective blocl; and in an adjacent block.

4. In a railway block signal system, a single electron discharge device in each block, means for controlling each of said discharge devices in accordance with the occupied condition of the respective block, indicating means in each block, and means controlled solely by said discharge devices for causing said indicating means in any block occupied by a vehicle to give a certain,

indication and the indicating means in an adjacent block to give a different indication.

5. In a railway block signal system, an electron discharge device in each block, means for controlling each of said discharge devices in accordance with the occupied conditions of the respective block, indicating means in each block, and means controlled by said discharge devices for causing said indicating means in any blockoccupied by a vehicleto give a certain indication, the indicating means in one of the adjacent blocks to give .a different indication, and

the indicating means in the opposite adjacent.

block to give a third indication.

6. In combination, a source of electromotive force, a circuit including said source and a plurality of electro-responsive devices, each of said electro-responsive devices being connected in a separate branch of said circuit, inductive means in each branch of said circuit, and means for controlling the inductance of said inductive means to cause selective response of said devices.

7. The combination, in a railway block signal system, a signal device in each block, a source of electromotive force, a circuit including said source and said signal device, an inductance device connected to control the energization of said signal device, and electron discharge means in each block for controlling the inductance of said inductance device in accordance with track conditions inone of said blocks.

8. The combination, in a railway block signal system,of a saturable reactor in each block, a plurality of signals in each block, and means including said saturable reactor for selectively controlling the signals in each block in response to the track conditions in the respective block and in an adjacent block said means including means for controlling the signals inresponse to the impedance of said reactor.

9. The combination, in a railway block signal system, of a plurality of signals in each block, a plurality of inductive reactors in each block so connected and arranged in circuit with said. signals that each signal is operative dependently upon the inductance of at least one associated accordance with theblock or blocks, occupied.

10. The combination, in a railway block sigrial system, of a plurality of signals in each lock, a plurality of inductive reactors in each blockso connected and arranged in circuit with said signals that each signal is operative dependently upon the inductance of at least one associated reactor, and means including an electron discharge device in each block, each of said discharge devices being responsive to the occupied condition of the respective block, for se- "lectively controlling the inductance of said reactors to cause operation of certain of said signals determined in accordance with the block or blocks occupied.

11. The combination, in a railway block signal system, of .a plurality of signals in each block,

a plurality of reactors in each block, each of said reactors having a winding the impedance of which is dependent upon the degree of saturation of the reactor, said windings being; so connected andarranged in circuit with said signals that each signal is operable dependently upon the degree of saturation or one or more asso-' ciated reactors, and means in each block for controlling theedegree of saturation of certain of said reactors in accordance with the occupied condition of the respective block.

12. The combination, in a railway block Signal,system, of .a plurality of signals in each block, a plurality of reactors in each block, each of said reactors having a winding the impedance of which is dependent upon the degree of saturation of the reactor, said windings being so connected and arranged in circuit with said signals that each signal is operable dependently upon the degree of saturation of at least one associated reactor, and means in each block for controlling the degree of saturation of certain oi -said reactors in the respective block; and in an adjacent block in accordance with the occupied condition or the respective blockthereby. to cause a different display of said signals in said blocks for different conditions of occupancy of said blocks. l V 13. Ina railway block signal system comprisinga plurality of blocks, a signal associated with each block, and electrical means-all of whose component parts are stationary with respect to each other, said electricalmeans being respon-- sive tothe presence of a vehicle in any block for operating the signal in thebloclg in advance of, the vehicle dependently upon the clear condi: tion of, the block in advance of the vehicle.

"14:11). a; railway block signal, system, a, plurality of signals in each: block, a. line conductor extending between a pair of adjacent blocks, and means for controlling a signal in eachblockof said pair of adjacentblocks over said conductor 'from'the other block of saidpair.

15. The combination, ina railway block signal system, or a vapor electric device in each block, means for supplying an electromotive'force to each of said vapor electric devices varying in accordance with the occupied conditionv of the respective block, said vapor electric device being adapted to break down, and pass current only when said electromotive force variesbeyond a predetermined value, a plurality of, signal devices, and means entirely electrical ,for. selectively anode circuit, means-for controlling each of; said vapor electric devices'in accordance with the occupied condition of the respective blocks, in-- ductive reactance means, means connected in the anode circuit of each of said devices to control the inductance'of saidreactance means, aplurality of signals in each'block, and means including said reactance means for selectively controlling said signals. 7

'17. The combination, a block signal system, of a plurality of signals ineach block, a pair of line conductors extending between each pair of adjacent blocks, and means for transmitting direct current from-any block to an adjacent block over said pair of line conductors extending' to said adjacent block and for transmitting alternating current to the opposite adjacent block over said-pair of line conductors extending to, said opposite adjacent block, and means for,

7 operating predetermined signals in said adjacent blocks in'response to-said currents.

18. The combination, in ablock signal system,

oi a. plurality: of signals ineach block, a pair of line conductorsextending between each pair of adjacent bloeksof said system, and means in one block of ,eachpair for sending direct current over said lineconductors to the opposite block of said pair and, meansin the opposite block forsending alternating, current over said line conductors to said one'block of theipair and means in each block for selectively controlling predetermined' signals in. response tov said currents.

19. In a railway block signal system, a pluralityv of: signalsin each block, ,a line conductor extendingbetween a; pairof adjacent blocks, and

means for controlling a, signal in each of said pair of adjacent blocks'over said conductor from the other block of said pair; said means including meansfor transmitting current in opposite directions "over said. conductor having different relative; intensities therebyselectively to control said signals. a

ZQM-TheEcOmbinatiOn, in a railway blocksignal system comprising a plurality of blocks, of clear, dangenandcaution signals in each block, a plurality, of" reactors in each block, said reactors being connectedland arranged selectively to controlisaidsigna-ls, and means operable dependently,

upon the, condition of' said-blocks selectively to.

control the inductance of said reactors to cause said dangernsignal to be actuated in any block' occupied by a vehicle, said, caution signal to be actuatedinanunoccupiedblock adjacent to and block occupiedby a vehicle, said caution signal to be actuated dependent upon the occupied'con dition' of'both or the two opposite adjacent-blocks,

and said clear. signal "to be energized dependent upon the unoccupied condition of one of said adjacent blocks and the occupied condition of the other adjacent block.

22. The combination, in a block signal system of a source of electromotive force in each block, a circuit in each block including said source and a plurality of signal devices, each of said signal devices being connected in a separate branch of said circuit, inductive means connected in each branch of said circuit, and means responsive to the condition of said blocks selectively to control the inductance of said inductive means tocause different signals to be actuated in any block in accordance with the difierent condition of occupancy of the respective block and an adjacent block.

23. The combination, in a railway block signal system, of a plurality of reactors in each block, each of said reactors having a winding the impedance of which is dependent upon the degree of saturation of the reactor, said windings being so connected selectively to control said signals that each signal is operable dependently upon the degree of saturation of at least one associated reactor, and means all of whose parts are stationary with respect to each other during opera tion selectively to control the saturation of said reactors in accordance with the track conditions in the different blocksthereby to cause dif ferent signals to be operated in accordance with different track conditions.

24. The combination, in a railway block signal system comprising a plurality of blocks, of a plurality of signals in each block, and means all of whose component parts are relatively stationary for selectively controlling said signals in accordance with the dififerent conditions of occupancy of adjacent blocks, said means comprising a plurality of saturable reactors in each block, means in each block selectively to control the saturation of certain of said reactors in response to track conditions in the different blocks, said reactors being so connected and arranged in circuit with said signals that different signals are actuated in accordance with the different conditions of occupancy of said blocks.

25. The combination, in a railway block signal system, of a plurality of signal devices in each block, a plurality of reactors in each block, each of said reactors having a winding, means all of whose component parts are stationary with respect to each other for controlling the saturation of said reactors in accordance with track conditions in the different blocks, said windings being so connected selectively to control said signal devices that as a vehicle traverses said blocks a certain signal device is actuated in any block occupied by said vehicle and either of two other signal devices is actuated in any block when unoccupied and immediately in advance of the vehicle, the signal device actuated being dependent upon whether a second block in advance of the vehicle is occupied or unoccupied.

26. The combination, in a block signal system, of means in each block for producing a plurality of signal indications, means in each block for controlling said last means to cause di'fierent signal indications to be produced dependent upon the condition of occupancy of the respective block and an adjacent block, said means including a saturable reactor, and means to control the saturation o-f said reactor in response to the condition of the respective block.

27. The combination, in a railway block signal system, of a magnetic device in each block having an iron core and a winding thereon, means to produce a unidirectional flux in said core, and means whereby the flux in the core of the magnetic device in any block may have either of two intensities dependent upon whether an adjacent block is occupied or unoccupied, and signal means connected to respond to changes in impedance of said winding due to changes in'intensity of said unidirectional flux.

28. The combination, in a railway block signal system, of a magnetic device in each block having a core and a winding thereon, means to produce unidirectional flux of either of two intensities in said core and tointerrupt said flux depending upon different track conditions in the respective block and an adjacent block, and a signal device controlled by the impedance of said wind- CHAUNCEY G. SUITS. 

